MADRID, Spain (CNN) -- A Bosnian suspect in the deadly Madrid train bombings has returned to Spain and surrendered to police, officials said.

Police arrested Sanel Sjekirika, 23, at the Madrid airport upon his return from Sweden late Friday, an Interior Ministry spokesman told CNN on Saturday. He offered no resistance.

Sjekirika was wanted by Spanish authorities on suspicion of financing Islamic terrorist activities.

In their investigation of Sjekirika, police discovered he had known a Tunisian man suspected of coordinating the March 11 attacks on Madrid commuter trains that killed 190 people, the spokesman said.

On Wednesday, Sjekirika told a Bosnian newspaper he was innocent and said he intended to return to Spain to turn himself in.

Sjekirika studied at the University of Oviedo in northern Spain, the spokesman said, and helped obtain university enrollment there and scholarship aid for Sarhane Ben Abdelmajid Fakhet.

Fakhet was described in an international arrest warrant as "coordinator" of the Madrid attacks.

He was one of seven suspected terrorists who blew themselves up April 3 in an apartment in the Madrid southern suburb of Leganes as police raided their hideout.

The remains of four of the suspects, including Fakhet, have been identified. DNA tests are being done to determine the identities of the other three, whose bodies were severely mangled.

On Friday, authorities said police had arrested three additional suspects in the Madrid area in connection with the March 11 attacks. (Full story)

Two of the suspects are from Saudi Arabia and Egypt -- the first time in the investigation that anyone from those countries has been detained, a National Court spokeswoman said. The third suspect is from Morocco.

Interior Minister Angel Acebes said police believe the Moroccan, who had been sought since March 11, knew others linked to the plot.

Acebes said police have evidence linking the Saudi and the Egyptian to some of the people who carried out the attacks, and they want to see if the two were involved or collaborated in any way.

The National Court has charged 18 people in the bombings, 14 of them Moroccans. The others charged are a Syrian, a Spaniard and two natives of India. Some of the 18 have been charged with mass murder in the deaths, while others face lesser charges of collaborating with a terrorist group.

Also Friday, a Spanish judge released without charges six Moroccans who had been suspected of playing a role in last month's bombings.